Reconstruct the cluster variable from a nlme model.
.getGroups2(object, ...)# S3 method for gls
.getGroups2(object, cluster, data, ...)
# S3 method for lme
.getGroups2(object, ...)
a gls or lme object.
[internal] Only used by the generic method.
the grouping variable relative to which the observations are iid.
the data set.
The variance coefficients that are exported are the residual variance of each outcome. This is \(\sigma^2\) for the first one and \(k^2 \sigma^2\) for the remaining ones.